Capacitor winding and capacitor provided with said capacitor winding

ABSTRACT

The invention is directed to a capacitor winding ( 9 ) having a layer stack ( 1 ) that is limited by two end faces ( 2 ) in a longitudinal direction and by one or more lateral surfaces ( 3 ) transverse to the longitudinal direction, comprises electrode layers ( 4 ) and parting layers ( 5 ) proceeding in longitudinal direction, and having a single-ply sheath ( 6 ) of electrically insulating material that covers the lateral surfaces ( 3 ) of the layer stack ( 1 ) gap-free and that comprises a projecting section ( 7 ) at an end face ( 2 ). The invention is also directed to a capacitor having the capacitor winding ( 9 ). The sheath ( 6 ) can be especially advantageously implemented as shrink hose that protects the capacitor winding ( 9 ) against damage upon insertion into a housing ( 10 ).

BACKGROUND OF THE INVENTION

[0001] The invention is directed to a capacitor winding having a layerstack that is limited by two end faces in a longitudinal direction andby one or more lateral surfaces transverse to the longitudinal directionand that comprises electrode layers and parting layers proceeding in thelongitudinal direction. The invention is also directed to a capacitorhaving the capacitor winding.

[0002] Capacitor windings of the species initially cited are known thatcomprise the shape of a cuboid and wherein the parting layers aresaturated with a liquid. These capacitor windings are usually installedin aluminum housings. For the electrical insulation of the capacitorwinding relative to the housing and in order to prevent the fluid fromrunning out of the capacitor winding, the known capacitor windings arecovered with plate-like insulating elements at each lateral surface.These plate-shaped insulating elements are additionally wound with amulti-ply binding.

[0003] The known capacitor windings have the disadvantage that there isnot adequate tightness at the abutting edges of the insulating plates,so that fluid can emerge from the capacitor winding. Although thebinder-shaped wrapping of the insulating plates sees to it that acompact package is produced from the layer stack and the insulatingplates, this arrangement cannot prevent the occurrence of trackingcurrents between a plurality of capacitor windings installed next to oneanother in a housing.

[0004] Since the capacitor windings are usually installed in acup-shaped housing by means of insertion, they also have thedisadvantage that the layers of the layer stack are inadequatelyprotected against damage at their end faces during the insertion. Theindividual layers of the layer stack can therefore be slightly damagedupon installation in the housing.

SUMMARY OF THE INVENTION

[0005] An object of the present invention is therefore to specify acapacitor winding that is protected against damage upon insertion into ahousing.

[0006] The object is achieved by a capacitor winding that comprises alayer stack. The layer stack is limited by two end faces in alongitudinal direction and by one or more lateral surfaces extendingtransverse to the longitudinal direction. The layer stack also compriseselectrode layers and parting layers proceeding in the longitudinaldirection. The capacitor winding is also provided with a single-plysheath of electrically insulating material that covers the lateralsurfaces of the layer stack gap-free and that has a projecting sectionat an end face.

[0007] The inventive capacitor winding has the advantage that aneffective protection of the edge of the layer stack upon insertion intoa cup-shaped housing is realized by means of the section of the sheathprojecting at an end face. However, it must thereby be noted that thelayer stack is inserted into the housing with the end face comprisingthe projecting section of the sheath in front.

[0008] The capacitor winding also has the advantage that the single-plysheath seals the layer stack in an especially space-saving way. Thegap-free covering of the lateral surfaces of the layer stack sees to anespecially good electrical insulation of the layer stack.

[0009] The projecting section of the sheath can, for example, befashioned collar-shaped and thereby extend in longitudinal direction ofthe layer stack. Such a projecting section can form a funnel or conicalend that is the leading part upon insertion of the layer stack into acup-shaped housing in order to protect the lateral edges of thecorresponding end face against damage due to the edges of the housing.

[0010] It is also especially advantageous when the projecting section ofthe sheath is folded over toward the inside and thereby covers an edgeregion of the end face. In this case, the edges of the layer stack canbe protected against damage upon insertion into the capacitor housingwithout employing additional measures.

[0011] The sheath can be fashioned in an especially space-saving way inthat it is under such a tensile stress that it conforms tightly to thesurface of the layer stack. An especially compact capacitor winding thatis correspondingly simple to handle is obtained as a result thereof.

[0012] For example, a sheath that resides under tensile stress andconforms tightly to the surface of the layer stack can be realized inthe form of a heat shrinkable tube or hose. The application of thesheath to the layer stack thereby assumes an especially simple formsince the shrinkable hose is pulled over the layer stack andsubsequently shrunken on by being heated. For example, polyvinylchloride (PVC) or polyester come into consideration as material for sucha heat shrinkable hose. These materials can be shrunken on by heatingthe layer stack to 220 degrees Celsius in a through-type furnace.

[0013] It is also advantageous when the sheath comprises a thickness of30 through 80 micrometers. Such a sheath has, on the one hand, adequatemechanical stability, so that it cannot be that easily damaged uponinsertion of the capacitor winding into a cup-shaped housing. On theother hand, it is adequately thin in order to realize a good volumeutilization and, thus, space saving for the capacitor winding.

[0014] Over and above this, a capacitor winding is especiallyadvantageous wherein the electrode layers are carbon cloths saturatedwith an ion-containing liquid and the parting layers are electricallyinsulating intermediate layers that are transmissive for the ion of theliquid. Further, an electrode layer is covered with an electricallyconductive contacting layer at one side and by a parting layer of afurther electrode layer at the other side.

[0015] Such a double layer capacitor can be especially effectivelyprotected against the emergence of the liquid by means of a sheathfashioned as the shrinkable hose or tube. Moreover, it is necessary inthe capacitor that has just been described that a contact pressure existbetween the electrode layers and the contacting layers. This contactpressure is usually realized by pressing the layer stack into a housinghaving corresponding dimensions. It is precisely in this case that thereis an increased risk of damage to the layer stack at the end facesduring insertion into the housing. The inventive sheath is thereforeespecially advantageous in this case.

[0016] The invention also specifies a capacitor having a capacitorwinding that is inserted into a housing open toward one end face of thecapacitor winding. The dimensions of the housing are thereby selectedsuch that the layers of the capacitor winding are pressed flat at a wallof the housing. Since the walls of the housing usually comprise a sharpedge caused by the manufacture and since the capacitor winding must beinserted into the open housing under pressure (otherwise, the layers ofthe capacitor winding would not be pressed flat at a wall), theinventive sheath that protects the edges of the end face of thecapacitor winding is especially advantageous in this case.

[0017] Further, a capacitor is especially advantageous wherein aplurality of capacitor windings are inserted side-by-side into thehousing such that their layers are pressed flat against a wall of thehousing.

[0018] In this case, the insulation of the capacitor windings from oneanother is also of particular significance. Such an insulation,particularly the prevention of tracking currents between the capacitorwindings, can be realized especially well by the inventive sheath thatcovers the lateral surfaces of the layer stack gap-free.

[0019] The housing can be closed by one or more terminating elements inorder to protect the capacitor against outside environmental influences.

[0020] The invention is explained in greater detail below on the basisof exemplary embodiments and the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a schematic cross-sectional view of an inventivecapacitor winding according to the present invention;

[0022]FIG. 2 is an enlarged cross-sectional view of a layer structure ofa capacitor winding of FIG. 1;

[0023]FIG. 3 is a schematic cross-sectional view of a capacitor with theinventive capacitor winding; and

[0024]FIG. 4 is a schematic cross-sectional view of a capacitor having aplurality of inventive capacitor windings installed in a housing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]FIG. 1 shows a capacitor winding 9 having a layer stack 1 thatcomprises the shape of a cuboid with two end faces 2 and four lateralsurfaces 3. The layer stack 1 comprises electrode layers 4 and partinglayers 5 stacked on top of one another. The layer stack 1 is surroundedby a sheath 6 that comprises a projecting section 7 at both end faces 2of the layer stack 1. Together with the sheath 6, the layer stack 1forms the capacitor winding 9. The sheath 6 is fashioned as shrink hoseor heat shrinkable tube that is shrunken onto the layer stack 1.

[0026]FIG. 2 shows a possible layer structure for the layer stack ofFIG. 1. Two electrode layers 4 are shown that are fashioned in the formof carbon cloths having a large surface at the sides facing toward oneanother. These carbon cloths are saturated with an ion-containingliquid. The electrode layers 4 are separated from one another by aparting layer 5. This parting layer 5 is an electrically insulatinglayer that, however, is transmissive for the ions of the liquid. Thisparting layer 5 can, for example, be a paper or, also, a polypropylenefilm.

[0027] The two electrode layers 4 are contacted by a contacting layer 8at their sides facing away from one another. This contacting layer canbe composed of, for example, aluminum. In order to assure a goodelectrical contact between the contacting layer 8 and the electrodelayer 4, it is necessary that the contacting layer 8 be pressed onto theelectrode layer 4.

[0028] Such a pressure is achieved by a capacitor according to FIG. 3wherein a capacitor winding having the layers described in FIG. 2,particularly an electrode layer 4 and a contacting layer 8, is installedin a cup-shaped housing 10. The dimensions of the housing 10,particularly the spacing between the walls 11, is selected such that thelayers 8, 4 situated in the capacitor winding 9 are pressed onto oneanother with a force F.

[0029] Terminal elements 13 are conducted out of the housing 10 forcontacting the capacitor winding 9. As a result of the inventive sheath(not shown in FIG. 3), the layer stack can also be inserted into thehousing 10 under pressure in the direction of the force F without theedges of the end faces of the capacitor winding 9 being damaged.

[0030]FIG. 4 shows a capacitor wherein a plurality of stacks 1 areinstalled in a housing 10 so that the individual layers are pressedagainst one another due to a corresponding spacing between the walls 11of the housing 10. In this case, the inventive sheath 6 has theadditional advantage that tracking currents between the individual layerstacks 1 can be effectively reduced.

[0031] The layer stacks 1 are provided with terminal elements 13 thatare respectively connected such to terminals elements 13 of theneighboring layer stack 1 by means of connector elements 14 that anelectrical series circuit of the layer stacks 1 occurs. The respectivelyoutermost terminal element 13 is connected to an outside terminal 15that is conducted through a terminating element 12 that closes thehousing 10. The connector elements 14 can, for example, be solderpoints. What is achieved by the selection of the dimensions of thehousing 10 is that the individual layers of the layer stack 1 arepressed onto one another by a force F.

[0032] The invention is not limited to the illustrated exemplaryembodiments but is defined by the following patent claims.

We claim:
 1. Capacitor winding having a layer stack (1) that is limitedby two end faces (2) in a longitudinal direction and by one or morelateral surfaces (3) transverse to the longitudinal direction, compriseselectrode layers (4) and parting layers (5) proceeding in longitudinaldirection, and having a single-ply sheath (6) of electrically insulatingmaterial that covers the lateral surfaces (3) of the layer stack (1)gap-free and that comprises a projecting section (7) at an end face (2).2. Capacitor winding according to claim 1, whereby the projectingsection (7) of the sheath (6) is collar-shaped and extends inlongitudinal direction.
 3. Capacitor winding according to claim 1,whereby the projecting section (70 of the sheath (6) is folded overtoward the inside and covers an edge region of the end face (2). 4.Capacitor winding according to claim 1 through 3, whereby the sheath (6)is under tensile stress such that is conforms tightly to the surface ofthe layer stack (1).
 5. Capacitor winding according to claim 4, wherebythe sheath (6) is a shrink hose.
 6. Capacitor winding according to claim1 through 5, whereby the sheath (6) comprises a thickness of 30 through80 μm.
 7. Capacitor winding according to claim 1 through 6, whereby theelectrode layers (4) are carbon cloths saturated with an ion-containingliquid and the parting layers (5) are electrically insulatingintermediate layers that are transmissive for the ion of the liquid, andwhereby an electrode layer (4) is covered with an electricallyconductive contacting layer (8) at one side and is separated by aparting layer (5) from a further electrode layer (4) at the other side.8. Capacitor having a capacitor winding (9) according to claim 1 through7 that is inserted into a housing (10) open toward an end face of thecapacitor winding (9), the dimensions of said housing (10) beingselected such that the layers (4, 5, 8) of the capacitor winding (9) arepressed flat at a wall (11) of the housing (10).
 9. Capacitor accordingto claim 8, whereby a plurality of capacitor windings (9) are insertedsuch into the housing (10) side-by-side that their layers (4, 5, 8) arepressed flat at a wall (11) of the housing (10).
 10. Capacitor accordingto claim 8 or 9, whereby the housing (10) is closed by one or moreterminating elements (12).